func_json: Enhance parsing capabilities of JSON_DECODE
Adds support for arrays to JSON_DECODE by allowing the user to print out entire arrays or index a particular key or print the number of keys in a JSON array. Additionally, adds support for recursively iterating a JSON tree in a single function call, making it easier to parse JSON results with multiple levels. A maximum depth is imposed to prevent potentially blowing the stack. Also fixes a bug with the unit tests causing an empty string to be printed instead of the actual test result. ASTERISK-29913 #close Change-Id: I603940b216a3911b498fc6583b18934011ef5d5b
This commit is contained in:
Naveen Albert
George Joseph
parent
f99849f8d5
commit
8a45cd7af4
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@ -0,0 +1,5 @@
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Subject: func_json
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Additional parsing capabilities have been added to the
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JSON_DECODE function, including support for arrays
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and recursive indexing.
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@ -1,7 +1,7 @@
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/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 2021, Naveen Albert
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* Copyright (C) 2021-2022, Naveen Albert
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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@ -54,6 +54,21 @@
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</parameter>
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<parameter name="item" required="true">
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<para>The name of the key whose value to return.</para>
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<para>Multiple keys can be listed separated by a hierarchy delimeter, which will recursively index into a nested JSON string to retrieve a specific subkey's value.</para>
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</parameter>
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<parameter name="separator" required="false">
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<para>A single character that delimits a key hierarchy for nested indexing. Default is a period (.)</para>
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<para>This value should not appear in the key or hierarchy of keys itself, except to delimit the hierarchy of keys.</para>
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</parameter>
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<parameter name="options" required="no">
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<optionlist>
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<option name="c">
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<para>For keys that reference a JSON array, return
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the number of items in the array.</para>
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<para>This option has no effect on any other type
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of value.</para>
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</option>
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</optionlist>
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</parameter>
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</syntax>
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<description>
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@ -69,19 +84,131 @@
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AST_THREADSTORAGE(result_buf);
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enum json_option_flags {
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OPT_COUNT = (1 << 0),
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};
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AST_APP_OPTIONS(json_options, {
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AST_APP_OPTION('c', OPT_COUNT),
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});
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#define MAX_JSON_STACK 32
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static int parse_node(char **key, char *currentkey, char *nestchar, int count, struct ast_json *json, char *buf, size_t len, int *depth)
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{
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const char *result = NULL;
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char *previouskey;
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struct ast_json *jsonval = json;
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/* Prevent a huge JSON string from blowing the stack. */
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if (*depth > MAX_JSON_STACK) {
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ast_log(LOG_WARNING, "Max JSON stack (%d) exceeded\n", MAX_JSON_STACK);
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return -1;
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}
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snprintf(buf, len, "%s", ""); /* clear the buffer from previous round if necessary */
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if (!json) { /* no error or warning should be thrown */
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ast_debug(1, "Could not find key '%s' in parsed JSON\n", currentkey);
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return -1;
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}
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switch(ast_json_typeof(jsonval)) {
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unsigned long int size;
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int r;
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case AST_JSON_STRING:
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result = ast_json_string_get(jsonval);
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ast_debug(1, "Got JSON string: %s\n", result);
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ast_copy_string(buf, result, len);
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break;
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case AST_JSON_INTEGER:
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r = ast_json_integer_get(jsonval);
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ast_debug(1, "Got JSON integer: %d\n", r);
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snprintf(buf, len, "%d", r); /* the snprintf below is mutually exclusive with this one */
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break;
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case AST_JSON_ARRAY:
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ast_debug(1, "Got JSON array\n");
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previouskey = currentkey;
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currentkey = strsep(key, nestchar); /* retrieve the desired index */
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size = ast_json_array_size(jsonval);
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ast_debug(1, "Parsed JSON array of size %lu, key: %s\n", size, currentkey);
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if (!currentkey) { /* this is the end, so just dump the array */
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if (count) {
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ast_debug(1, "No key on which to index in the array, so returning count: %lu\n", size);
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snprintf(buf, len, "%lu", size);
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return 0;
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} else {
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char *result2 = ast_json_dump_string(jsonval);
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ast_debug(1, "No key on which to index in the array, so dumping '%s' array\n", previouskey);
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ast_copy_string(buf, result2, len);
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ast_json_free(result2);
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}
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} else if (ast_str_to_int(currentkey, &r) || r < 0) {
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ast_debug(1, "Requested index '%s' is not numeric or is invalid\n", currentkey);
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} else if (r >= size) {
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ast_debug(1, "Requested index '%d' does not exist in parsed array\n", r);
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} else {
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struct ast_json *json2 = ast_json_array_get(jsonval, r);
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if (!json2) {
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ast_debug(1, "Array index %d contains empty item\n", r);
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return -1;
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}
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previouskey = currentkey;
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currentkey = strsep(key, nestchar); /* get the next subkey */
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ast_debug(1, "Recursing on index %d in array (key was '%s' and is now '%s')\n", r, previouskey, currentkey);
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/* json2 is a borrowed ref. That's fine, since json won't get freed until recursing is over */
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/* If there are keys remaining, then parse the next object we can get. Otherwise, just dump the child */
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if (parse_node(key, currentkey, nestchar, count, currentkey ? ast_json_object_get(json2, currentkey) : json2, buf, len, depth)) { /* recurse on this node */
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return -1;
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}
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}
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break;
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case AST_JSON_OBJECT:
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default:
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ast_debug(1, "Got generic JSON object for key %s\n", currentkey);
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if (!currentkey) { /* this is the end, so just dump the object */
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char *result2 = ast_json_dump_string(jsonval);
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ast_copy_string(buf, result2, len);
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ast_json_free(result2);
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} else {
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previouskey = currentkey;
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currentkey = strsep(key, nestchar); /* retrieve the desired index */
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ast_debug(1, "Recursing on object (key was '%s' and is now '%s')\n", previouskey, currentkey);
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if (parse_node(key, currentkey, nestchar, count, ast_json_object_get(jsonval, currentkey), buf, len, depth)) { /* recurse on this node */
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return -1;
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}
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}
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break;
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}
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return 0;
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}
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static int json_decode_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
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{
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struct ast_json *json, *jsonval;
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int count = 0;
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struct ast_flags flags = {0};
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struct ast_json *json = NULL;
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char *nestchar = "."; /* default delimeter for nesting key indexing is . */
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int res, depth = 0;
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AST_DECLARE_APP_ARGS(args,
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AST_APP_ARG(varname);
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AST_APP_ARG(key);
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AST_APP_ARG(nestchar);
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AST_APP_ARG(options);
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);
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char *varsubst, *result2;
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const char *result = NULL;
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char *varsubst, *key, *currentkey, *nextkey, *firstkey, *tmp;
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struct ast_str *str = ast_str_thread_get(&result_buf, 16);
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AST_STANDARD_APP_ARGS(args, data);
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if (!ast_strlen_zero(args.options)) {
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ast_app_parse_options(json_options, &flags, NULL, args.options);
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if (ast_test_flag(&flags, OPT_COUNT)) {
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count = 1;
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}
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}
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if (ast_strlen_zero(args.varname)) {
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ast_log(LOG_WARNING, "%s requires a variable name\n", cmd);
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return -1;
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@ -90,6 +217,15 @@ static int json_decode_read(struct ast_channel *chan, const char *cmd, char *dat
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ast_log(LOG_WARNING, "%s requires a key\n", cmd);
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return -1;
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}
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key = ast_strdupa(args.key);
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if (!ast_strlen_zero(args.nestchar)) {
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int seplen = strlen(args.nestchar);
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if (seplen != 1) {
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ast_log(LOG_WARNING, "Nesting separator '%s' has length %d and is invalid (must be a single character)\n", args.nestchar, seplen);
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} else {
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nestchar = args.nestchar;
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}
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}
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varsubst = ast_alloca(strlen(args.varname) + 4); /* +4 for ${} and null terminator */
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if (!varsubst) {
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@ -98,45 +234,43 @@ static int json_decode_read(struct ast_channel *chan, const char *cmd, char *dat
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}
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sprintf(varsubst, "${%s}", args.varname); /* safe, because of the above allocation */
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ast_str_substitute_variables(&str, 0, chan, varsubst);
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ast_debug(1, "Parsing JSON using nesting delimeter '%s'\n", nestchar);
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if (ast_str_strlen(str) == 0) {
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ast_debug(1, "Variable '%s' contains no data, nothing to search!\n", args.varname);
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return -1; /* empty json string */
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}
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ast_debug(1, "Parsing JSON: %s\n", ast_str_buffer(str));
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/* allow for multiple key nesting */
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currentkey = key;
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firstkey = ast_strdupa(currentkey);
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tmp = strstr(firstkey, nestchar);
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if (tmp) {
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*tmp = '\0';
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}
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/* parse a string as JSON */
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ast_debug(1, "Parsing JSON: %s (key: '%s')\n", ast_str_buffer(str), currentkey);
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if (ast_strlen_zero(currentkey)) {
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ast_debug(1, "Empty JSON key\n");
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return -1;
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}
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if (ast_str_strlen(str) == 0) {
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ast_debug(1, "JSON node '%s', contains no data, nothing to search!\n", currentkey);
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return -1; /* empty json string */
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}
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json = ast_json_load_str(str, NULL);
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if (!json) {
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ast_log(LOG_WARNING, "Failed to parse as JSON: %s\n", ast_str_buffer(str));
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return -1;
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}
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jsonval = ast_json_object_get(json, args.key);
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if (!jsonval) { /* no error or warning should be thrown */
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ast_debug(1, "Could not find key '%s' in parsed JSON\n", args.key);
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ast_json_unref(json);
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return -1;
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}
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switch(ast_json_typeof(jsonval)) {
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int r;
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case AST_JSON_STRING:
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result = ast_json_string_get(jsonval);
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snprintf(buf, len, "%s", result);
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break;
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case AST_JSON_INTEGER:
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r = ast_json_integer_get(jsonval);
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snprintf(buf, len, "%d", r); /* the snprintf below is mutually exclusive with this one */
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break;
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default:
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result2 = ast_json_dump_string(jsonval);
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snprintf(buf, len, "%s", result2);
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ast_json_free(result2);
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break;
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}
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/* parse the JSON object, potentially recursively */
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nextkey = strsep(&key, nestchar);
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res = parse_node(&key, nextkey, nestchar, count, ast_json_object_get(json, firstkey), buf, len, &depth);
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ast_json_unref(json);
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return 0;
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return res;
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}
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static struct ast_custom_function json_decode_function = {
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@ -151,12 +285,26 @@ AST_TEST_DEFINE(test_JSON_DECODE)
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struct ast_channel *chan; /* dummy channel */
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struct ast_str *str; /* fancy string for holding comparing value */
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const char *test_strings[][5] = {
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{"{\"city\": \"Anytown\", \"state\": \"USA\"}", "city", "Anytown"},
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{"{\"city\": \"Anytown\", \"state\": \"USA\"}", "state", "USA"},
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{"{\"city\": \"Anytown\", \"state\": \"USA\"}", "blah", ""},
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{"{\"key1\": \"123\", \"key2\": \"456\"}", "key1", "123"},
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{"{\"key1\": 123, \"key2\": 456}", "key1", "123"},
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const char *test_strings[][6] = {
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{"{\"city\": \"Anytown\", \"state\": \"USA\"}", "", "city", "Anytown"},
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{"{\"city\": \"Anytown\", \"state\": \"USA\"}", "", "state", "USA"},
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{"{\"city\": \"Anytown\", \"state\": \"USA\"}", "", "blah", ""},
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{"{\"key1\": \"123\", \"key2\": \"456\"}", "", "key1", "123"},
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{"{\"key1\": 123, \"key2\": 456}", "", "key1", "123"},
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{"{ \"path\": { \"to\": { \"elem\": \"someVar\" } } }", "/", "path/to/elem", "someVar"},
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{"{ \"path\": { \"to\": { \"elem\": \"someVar\" } } }", "", "path.to.elem2", ""},
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "/", "path/to/arr/2", ""}, /* nonexistent index */
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "/", "path/to/arr/-1", ""}, /* bogus index */
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "/", "path/to/arr/test", ""}, /* bogus index */
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "", "path.to.arr.test.test2.subkey", ""}, /* bogus index */
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", ",c", "path.to.arr", "2"}, /* test count */
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "", "path.to.arr", "[\"item0\",\"item1\"]"},
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", ".", "path.to.arr.1", "item1"},
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "/", "path/to/arr", "[\"item0\",\"item1\"]"},
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "/", "path/to/arr/1", "item1"},
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{"{ \"path\": { \"to\": { \"arr\": [ {\"name\": \"John Smith\", \"phone\": \"123\"}, {\"name\": \"Jane Doe\", \"phone\": \"234\"} ] } } }", ",c", "path.to.arr.0.name", "John Smith"},
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{"{ \"path\": { \"to\": { \"arr\": [ {\"name\": 1, \"phone\": 123}, {\"name\": 2, \"phone\": 234} ] } } }", ",c", "path.to.arr.0.name", "1"},
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{"{ \"path\": { \"to\": { \"arr\": [ {\"name\": [ \"item11\", \"item12\" ], \"phone\": [ \"item13\", \"item14\" ]}, {\"name\": [ \"item15\", \"item16\" ], \"phone\": [ \"item17\", \"item18\" ]} ] } } }", ",c", "path.to.arr.0.name.1", "item12"},
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};
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switch (cmd) {
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@ -182,7 +330,7 @@ AST_TEST_DEFINE(test_JSON_DECODE)
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}
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for (i = 0; i < ARRAY_LEN(test_strings); i++) {
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char tmp[512], tmp2[512] = "";
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char tmp[512];
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struct ast_var_t *var = ast_var_assign("test_string", test_strings[i][0]);
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if (!var) {
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@ -194,11 +342,11 @@ AST_TEST_DEFINE(test_JSON_DECODE)
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AST_LIST_INSERT_HEAD(ast_channel_varshead(chan), var, entries);
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snprintf(tmp, sizeof(tmp), "${JSON_DECODE(%s,%s)}", "test_string", test_strings[i][1]);
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snprintf(tmp, sizeof(tmp), "${JSON_DECODE(%s,%s,%s)}", "test_string", test_strings[i][2], test_strings[i][1]);
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ast_str_substitute_variables(&str, 0, chan, tmp);
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if (strcmp(test_strings[i][2], ast_str_buffer(str))) {
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ast_test_status_update(test, "Format string '%s' substituted to '%s'. Expected '%s'.\n", test_strings[i][0], tmp2, test_strings[i][2]);
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if (strcmp(test_strings[i][3], ast_str_buffer(str))) {
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ast_test_status_update(test, "Format string '%s' substituted to '%s' (key: %s). Expected '%s'.\n", test_strings[i][0], ast_str_buffer(str), test_strings[i][2], test_strings[i][3]);
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res = AST_TEST_FAIL;
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}
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}
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@ -214,7 +362,9 @@ static int unload_module(void)
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{
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int res;
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#ifdef TEST_FRAMEWORK
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AST_TEST_UNREGISTER(test_JSON_DECODE);
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#endif
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res = ast_custom_function_unregister(&json_decode_function);
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return res;
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@ -224,7 +374,9 @@ static int load_module(void)
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{
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int res;
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#ifdef TEST_FRAMEWORK
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AST_TEST_REGISTER(test_JSON_DECODE);
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#endif
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res = ast_custom_function_register(&json_decode_function);
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return res;
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